Device for stretching fabric



Feb. 27, 1968 D. c. CUMBERS 3,370,364

DEVICE FOR STRETCHING FABRIC Filed June 7, 1965 3 Sheets-Sheet 1 Inventor D0 V/D Cawfizafa/wms Attorneys Feb. 27, 1968 D. c. CUMBERS 3,370,364

DEVICE FOR STRETCHING FABRIC Filed June 7, 1965 3 Sheets-Sheet 2 FIG.5

lnvenior DAV/0 62 /9545; aa/vae/as' Attorneys Feb. 27, 1968 D. C. CUMBERS DEVICE FOR STRETCHING FABRIC Filed June 7, 1965 5 Sheets-Sheet 3 1:. w 30 32 Flea Inventor 2A :00 CAMFAES 60/754 55 Attorneys United States Patent 3,370,364 DEVICE FOR STRETCHING FABRIC David C. Cumbers, Pontypool, England, assignor to British Nylon Spinners Limited, Pontypool, England Filed June 7, 1965, Ser. No. 461,856

Claims priority, application Great Britain, June 9, 1964,

23,781/ 64 3 Claims. (Cl. 38-102.4)

ABSTRACT OF THE DISCLOSURE A stenter comprising a pair of oppositely disposed, spaced-apart, inwardly-facing channel members slidably disposed in an outer casing which has a longitudinal slot therein coextensive with the channel members. A plurality of fabric holding pins extend from the slot and are carried by an expansible and contractible lattice disposed within the channel members. The lattice includes a plurality of arm members having opposite ends slidable in the channel members and link members pivotally interconnecting one end of each arm member to the midpoint of the adjacent arm member.

This invention is concerned with stenters or the like used, for example, in the stretching of drying of fabrics.

In the stentering of a piece of fabric it is customary practice for the fabric to be gripped along its opposite edges by the stentering holding devices which, in the case of a continuous stenter, are mounted on links on two traveling chains of the machine. As is known, provision may be made in the stenters commonly available for imparting a sideways stretch in the fabric passing therethrough, but it is not possible to stretch the fabric in 'the longitudinal direction.

An object of the present invention is to provide a stenter wherein the fabric may be stretched in two mutually transverse directions substantially simultaneously.

One means of accomplishing this object is by the use of an expansible and contractible lattice construction upon which the fabric holding means are mounted.

The lattice construction may comprise a number of scissor-action arms articulated to one another at or close to their ends and pivotally interconnected in pairs between the points of articulation. In such a construction the movement of one pair of arms (as a result, for example, of tension in the fabric being processed) is transmitted thrOugh the articulations to the adjoining pairs of arms so that all the pairs of arms take up identical angular positions, which in turn ensures constant and identical spacing of the fabric holding means associated with each pair of arms in any angular position thereof. However, this construction, as will be shown hereinafter, has certain defects. Alternatively, the lattice construction may comprise a plurality of members connected together in an articulated manner by transverse link arms, one end of each of which link arms being pivotally secured to one member and the other end pivotally secured to an adjacent member.

Conveniently the fabric holding means takes the form of upstanding pins.

Accordingly, the present invention in one of its aspects resides in the provision of a stenter comprising limbs in each of which limbs the fabric holding means, in the form of pins, are mounted in a row on an expansible and contractible lattice which lattice comprises a plurality of members connected together by transverse link arms, one end of each link arm being pivotally secured to one member and the other end pivotally secured to an adjacent member wherein one end of each member has a fabric holding pin mounted thereon, the opposite ends of the members being so located in guide channels that the ends carrying the pins are constrained to move longitudinally of their guide channel along a slot therein while the other ends can move arcuately whereby the distance between adjacent pins can vary freely and independently of one another along said slot.

Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings wherein:

' FIGURE 1 is a perspective view showing one limb of a stenter incorporating the lattice construction of the present invention;

FIGURE 2 shows diagrammatically details of the lattice construction of FIGURE 1;

FIGURE 3 is an enlarged cross section of the limb shown in FIGURE 1;

FIGURES 4 and 5 illustrate a modified structure embodying a scissor-action.

FIGURE 6 is a schematic plan view of one type of stenter, in this instance, a single piece stenter incorporating the lattice construction of the present invention.

Referring firstly to FIGURES 1 to 3, a plurality of horizontal arms 11 are interconnected in an expansible any contractible manner through transverse link-arms 12A and 128. Each of the arms 12A and 12B is pivotally attached to one end of an arm 11 by an upstanding tapered pin 13 which serves as the fabric holding means, and secured to the adjacent arm 11 at its mid-point 14.

This lattice construction is located in an inner casing 15 of the limb, indicated generally by reference numeral 16, of the stenter. The inner casting 15 comprises two side limbs 17 and 18 of channel form according to U-sectional shape shown in FIGURES l and 3 wherein the channels are indicated by reference numerals 19 and 20, and a horizontal slat 21 which co-operates with side limb 18 to provide a slot 22 through which projects the fabric holding means 13.

The inner casing 15 is positioned within an integral outer-casing 23, the upper surface 24 of which contains a slot 25 adjacent to and co-axial with slot 22, the upstanding pins 13 projecting through said slot.

In the use of the stenter, the fabric is held in position by means of the upstanding pins 13 over which the fabric is placed, and any forces which develop because of tension in the fabric, for example, in sideways stretching of the fabric, are transmitted through the upstanding pins, which are constrained from lateral movement by the longitudinal slot (22, 25), to the lattice construction on which they are mounted, whereby expansion of the lattice construction is effected.

In this particular lattice construction, the arms 11 which carry the upstanding pins 13, move independently of each other, so that the distance between adjacent pins may vary. This independent pin movement is reflected in the absence of localised variations in tension in the fabric held by the pins, and arising, for example, from uneven initial tension in the fabric. In the fabric exhibits an uneven tension when placed on the pins, the distance between pins would automatically be adjusted, in consequence of movement of the arms 11 which carry them, to eliminate the tension variations.

On expansion, the horizontal arms 11, opposed ends of which arms are located in channels 19 and 20, respectively, of the inner casing 15, slide along said channels. This sliding movement is accompanied by an opening out of transverse link arms 12A and 128 which then make a more obtuse angle with the horizontal arm 11 to which they are joined.

The sliding movement described above may be facilitated by providing channels 19 and 20 with a low friction surface. Such a low friction surface may be provided by coating the inner surfaces of the channels with polytetrafiuoroethylene.

If the transverse link arms 12A and 12B were connected to opposed ends of adjacent arms 11 there would be a tendency for the lattice construction to twist because of the torque exerted on the arms 11'by the upstanding pin 13. This tendency is minimized by the construction shown in FIGURES 1-3 wherein horizontal arm 11 is provided with an extended tail 26 which is held in abutment with the roof of channel 19.

FIGURES 4 and show a modified lattice construction which comprises a plurality of horizontal arms 27 connected together in scissor-action fashion by pivot pins 28, the axis of each pivot pin passing through the axis of articulation. The arms 27 carry, at one end thereof, upstanding pins 28' which serve as the fabric holding means.

Utilization of this scissors-action construction permits a positive movement of every pin without tension from the fabric but it has certain defects, in particular, should the fabric be pinned onto the upstanding pins in an uneven fashion variations in tension develop and persist during stretching since the angular position of all arms is identical and the pins are always equally spaced and perhaps more importantly, there is a greater tendency for the scissor-action armsto become distorted and this may lead to jamming. Referring to FIGURE 6, the single piece stenter comprises a rectangular frame made up of four limbs 28", 29, 30 and 31, each of which serves as, and

a is similar to, the outer casing 23 shown in FIGURES 1-3.

Inside each of the four limbs there is located an inner casing which is movable in said limb. In each of the four inner casings there is positioned a lattice construction identical to that'shown in FIGURES 1-3, one end of each lattice being secured to the inner surface of the outer casing, the other end being connected to the similar end'of the lattice of an adjacent limb. For ease of illustration only the slots 22 and 25 and the pins 13 are illustrated in FIGURE 6, the slat 21 and the arms 11, 12a and 12b of FIGURE 1 being omitted. Opposed limbs of the rectangular frame are connected by rods 32 and 33. Opposite ends of each of the rods 32 and 33 are provided with screw threads of opposite pitch (not shown) so that turning them moves the limbs away from or toward the centre hub 40 into which one end of each of the threaded rods engages. Each of the rods 32 and 33 may be turned manually.

In the use of the stenter frame a rectangular sheet of fabric is attached along its'edges by means of upstanding pins 13, and the push-pull rods are operated so that the four limbs 2831 are pushed outwards, the inner casings move within the outer, the lattice constructions Within each of the inner casings slide therewith, and the fabric is stretched by the desired amount. The amount of stretch 4 can be varied by a suitable adjustment of the push-pull rods 32, 33. In this regard it will be understood that rotation of any rod in a given direction either pulls the respective limb toward the hub or pushes it away from the hub, as a result of the opposite threads at the ends of the rod.

Such a stenter is very useful for investigating the behaviour of a variety of fabrics under different stentering conditions, for' example, at different temperatures and different tensions.

What I claim is:

l. A stenter for stretching fabrics comprising: at least two spaced apart opposed limbs, each of said limbs defining two, oppositely-disposed, inwardly-facing guide channels and a longitudinally extending slot between them; an expansible and contractible lattice for each limb including a plurality of arm members connected together by link members, one end of each link member being pivotally secured to one arm member and the other end pivotally secured to an adjacent arm member; a plurality of fabric-holding pins, each mounted on one of said arm members near one end thereof and extending through said slot; the opposite'ends of each arm member being located in said inwardly facing guide channels so that the ends carrying said pins are constrained to move longitudinally of their guide channel while the other ends can move arcuately whereby the distance between adjacent pins can vary freely and independently along said slot, and means for moving said limbs away from each other so as to place a piece of fabric mounted on said pins in tension, whereby the resulting forces on said pinsare transmitted to said lattice to cause the latter to expand.

2. Apparatus as in claim 1 wherein each of said limbs includes an outer casing and two inner channel members slidably disposed in said casing and defining said guide channels.

3. Apparatus as in claim .1 wherein said other ends of said link members are pivotally secured to the respective arm members at about the midpoints of said arm members.

References Cited UNITED STATES PATENTS 2,309,076 1/1943 Morondo 38l02.91 XR 2,455,640 12/1948 Ashbaugh 38-10291 XR 2,759,217 8/1956 Peterson 26-54 XR 2,761,192 9/1956 Kohle 26-62 XR 2,923,966 2/1960 Tooke et al. 2657 XR 3,148,409 9/1964 Bruckner 2657 XR FOREIGN PATENTS 112,553 1/1918 Great Britain.

ROBERT R. MACKEY, Primary Examiner. 

